Introduction to Enzymes

The following has been excerpted from a very popular Worthington publication
which was originally published in 1972 as the Manual of Clinical Enzyme
Measurements. While some of the presentation may seem somewhat dated, the
basic concepts are still helpful for researchers who must use enzymes but
who have little background in enzymology.

Chemical Equilibrium

The study of a large number of chemical reactions reveals that most do not go to true completion. This is likewise true of enzymatically-catalyzed reactions. This is due to the reversibility of most reactions. In general:

where K+1 is the forward reaction rate constant and K-1 is the rate constant for the reverse reaction.

Combining the two reactions gives:

Applying this general relationship to enzymatic reactions allows the equation:

Equilbrium, a steady state condition, is reached when the forward reaction rates equal the backward rates. This is the basic equation upon which most enzyme activity studies are based.